Polarization of Pc1 Geomagnetic Pulsations as an Indicator of the Position of Their Source

The article considers the scenario of the propagation of geomagnetic pulsations Pc1 from the region of their generation in the magnetosphere to a ground-based receiver, including the ionospheric waveguide (in the F2 layer), where magnetospheric Alfven (i.e. left-handpolarized) waves are transformed into fast, magnetosonic (right-handpolarized) waves. Left-handed wave polarization should be observed near the projection of the Pc1 source on the Earth's surface, while polarization is right-handed at a considerable distance. The latitudinal distribution pattern of the Pc1 polarization on the Finnish meridional profile of induction magnetometers at 57 degrees-66 degrees MLAT latitudes have been studied based on a large array of observational data (more than 200 Pc1 events). Mixed polarization was observed at stations in the overwhelming majority of cases, which may due to the considerable distance of this profile from the projection of the Pc1 pulsation source. An analysis of events with a clear left - or right-handpolarization showed that left-handpolarized waves were observed, as a rule, in the vicinity of a possible projection of the plasmapause (the most probable region of the generation of geomagnetic pulsations Pc1) and that they were replaced by right-handpolarized waves of the same frequency range with increasing distance. This implies that the left-handed polarization of Pc1 waves on the Earth's surface can be an indicator of the position of the projection of their source.